{"action":"created","comment":{"url":"https://api.github.com/repos/apache/couchdb/pulls/comments/143801114","pull_request_review_id":68366914,"id":143801114,"diff_hunk":"@@ -143,11 +146,11 @@ handle_call(Msg, _From, St) ->\n \n \n handle_cast({evict, DbName}, St) ->\n-    gen_server:abcast(mem3:nodes(), ?MODULE, {do_evict, DbName}),\n+    gen_server:abcast(mem3:nodes(), ?OPENER, {do_evict, DbName}),\n     {noreply, St};\n \n handle_cast({refresh, DbName, DDocIds}, St) ->\n-    gen_server:abcast(mem3:nodes(), ?MODULE, {do_refresh, DbName, DDocIds}),\n+    gen_server:abcast(mem3:nodes(), ?OPENER, {do_evict, DbName, DDocIds}),","path":"src/ddoc_cache/src/ddoc_cache_lru.erl","position":20,"original_position":20,"commit_id":"74c22adc601cd3cf5e1497c87b3942d3d402defd","original_commit_id":"74c22adc601cd3cf5e1497c87b3942d3d402defd","user":{"login":"davisp","id":19929,"avatar_url":"https://avatars3.githubusercontent.com/u/19929?v=4","gravatar_id":"","url":"https://api.github.com/users/davisp","html_url":"https://github.com/davisp","followers_url":"https://api.github.com/users/davisp/followers","following_url":"https://api.github.com/users/davisp/following{/other_user}","gists_url":"https://api.github.com/users/davisp/gists{/gist_id}","starred_url":"https://api.github.com/users/davisp/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/davisp/subscriptions","organizations_url":"https://api.github.com/users/davisp/orgs","repos_url":"https://api.github.com/users/davisp/repos","events_url":"https://api.github.com/users/davisp/events{/privacy}","received_events_url":"https://api.github.com/users/davisp/received_events","type":"User","site_admin":false},"body":"Yes, that's the fix.\r\n\r\nhttps://github.com/apache/couchdb/blob/master/src/ddoc_cache/src/ddoc_cache_opener.erl#L47-L55\r\n\r\nIts reverting the message passing protcol to match the old version. For old nodes this means they continue to behave the same. For new nodes, the ddoc_cache_opener module exists solely to forward and translate the old style messages to new style. My mistake was just not realizing that ddoc_cache_lru wouldn't be silently ignored by the old version (because the ets_lru process exists).","created_at":"2017-10-10T17:40:58Z","updated_at":"2017-10-10T17:40:59Z","html_url":"https://github.com/apache/couchdb/pull/886#discussion_r143801114","pull_request_url":"https://api.github.com/repos/apache/couchdb/pulls/886","author_association":"MEMBER","_links":{"self":{"href":"https://api.github.com/repos/apache/couchdb/pulls/comments/143801114"},"html":{"href":"https://github.com/apache/couchdb/pull/886#discussion_r143801114"},"pull_request":{"href":"https://api.github.com/repos/apache/couchdb/pulls/886"}},"in_reply_to_id":143799811},"pull_request":{"url":"https://api.github.com/repos/apache/couchdb/pulls/886","id":145754891,"html_url":"https://github.com/apache/couchdb/pull/886","diff_url":"https://github.com/apache/couchdb/pull/886.diff","patch_url":"https://github.com/apache/couchdb/pull/886.patch","issue_url":"https://api.github.com/repos/apache/couchdb/issues/886","number":886,"state":"open","locked":false,"title":"Fix cluster upgrades when deploying ddoc_cache","user":{"login":"davisp","id":19929,"avatar_url":"https://avatars3.githubusercontent.com/u/19929?v=4","gravatar_id":"","url":"https://api.github.com/users/davisp","html_url":"https://github.com/davisp","followers_url":"https://api.github.com/users/davisp/followers","following_url":"https://api.github.com/users/davisp/following{/other_user}","gists_url":"https://api.github.com/users/davisp/gists{/gist_id}","starred_url":"https://api.github.com/users/davisp/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/davisp/subscriptions","organizations_url":"https://api.github.com/users/davisp/orgs","repos_url":"https://api.github.com/users/davisp/repos","events_url":"https://api.github.com/users/davisp/events{/privacy}","received_events_url":"https://api.github.com/users/davisp/received_events","type":"User","site_admin":false},"body":"## Overview\r\n\r\nAs it turns out I made a bit of a mistake when I forgot that the old\r\nddoc_cache implementation had an ets_lru process registered as\r\nddoc_cache_lru. These cast messages were causing that process to crash.\r\nIf a cluster had enough design document activity and enough nodes this\r\nwould cause nodes with the old ddoc_cache implementation to reboot the\r\nentire VM. This was a cascading failure due to the ets_lru process\r\nrestarting frequently enough that it brought down the entire ddoc_cache\r\napplication.\r\n\r\n## Testing recommendations\r\n\r\nTry a rolling reboot upgrade of a large cluster with significant write load on design documents.\r\n\r\n## Checklist\r\n\r\n- [x] Code is written and works correctly;\r\n- [x] Changes are covered by tests;\r\n- [ ] Documentation reflects the changes;\r\n","created_at":"2017-10-10T17:31:59Z","updated_at":"2017-10-10T17:40:59Z","closed_at":null,"merged_at":null,"merge_commit_sha":"c11bfc420864ef4ce9d6c990c8b54f89146937ce","assignee":null,"assignees":[],"requested_reviewers":[],"milestone":null,"commits_url":"https://api.github.com/repos/apache/couchdb/pulls/886/commits","review_comments_url":"https://api.github.com/repos/apache/couchdb/pulls/886/comments","review_comment_url":"https://api.github.com/repos/apache/couchdb/pulls/comments{/number}","comments_url":"https://api.github.com/repos/apache/couchdb/issues/886/comments","statuses_url":"https://api.github.com/repos/apache/couchdb/statuses/74c22adc601cd3cf5e1497c87b3942d3d402defd","head":{"label":"apache:fix-ddoc-cache-upgrade","ref":"fix-ddoc-cache-upgrade","sha":"74c22adc601cd3cf5e1497c87b3942d3d402defd","user":{"login":"apache","id":47359,"avatar_url":"https://avatars0.githubusercontent.com/u/47359?v=4","gravatar_id":"","url":"https://api.github.com/users/apache","html_url":"https://github.com/apache","followers_url":"https://api.github.com/users/apache/followers","following_url":"https://api.github.com/users/apache/following{/other_user}","gists_url":"https://api.github.com/users/apache/gists{/gist_id}","starred_url":"https://api.github.com/users/apache/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/apache/subscriptions","organizations_url":"https://api.github.com/users/apache/orgs","repos_url":"https://api.github.com/users/apache/repos","events_url":"https://api.github.com/users/apache/events{/privacy}","received_events_url":"https://api.github.com/users/apache/received_events","type":"Organization","site_admin":false},"repo":{"id":206417,"name":"couchdb","full_name":"apache/couchdb","owner":{"login":"apache","id":47359,"avatar_url":"https://avatars0.githubusercontent.com/u/47359?v=4","gravatar_id":"","url":"https://api.github.com/users/apache","html_url":"https://github.com/apache","followers_url":"https://api.github.com/users/apache/followers","following_url":"https://api.github.com/users/apache/following{/other_user}","gists_url":"https://api.github.com/users/apache/gists{/gist_id}","starred_url":"https://api.github.com/users/apache/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/apache/subscriptions","organizations_url":"https://api.github.com/users/apache/orgs","repos_url":"https://api.github.com/users/apache/repos","events_url":"https://api.github.com/users/apache/events{/privacy}","received_events_url":"https://api.github.com/users/apache/received_events","type":"Organization","site_admin":false},"private":false,"html_url":"https://github.com/apache/couchdb","description":"Apache 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